In telecommunications, transmissions are often performed by means of block transmission schemes. It is then common to use guard intervals (GI) to ensure that distinct blocks do not interfere with one another. The guard intervals are for example cyclic prefixes, zero-paddings, or pseudo-noise sequences.
The use of guard intervals combats intersymbol interference and intercarrier interference. In the guard interval, no or only redundant information is transmitted. This seriously limits the spectral efficiency of block transmission schemes. For example, a telecommunication system with a guard interval whose length is a quarter of the block length, 20% of the time (and thus of the achievable throughput) is wasted.
“Precoder for DMT with insufficient cyclic prefix” in Proc. IEEE International Conference on Communications, 1998, vol. 1, pp. 339-343 by Kok-Wui Cheong and J. M. Cioffi describes the introduction of a precoder at the transmitter intended to reduce distortions due to insufficient length of the cyclic prefix used in the guard interval. The precoder is arranged to reduce the distortion by processing the signals at the transmitter such that the signals appear to be undistorted at the receiver.